what causes 'chatter' breakdown?

[jvanick]

Just wanted to post a quick update on this...

my rep at our supply company told me that there's a specially forumulated SP1400 called SP1400-W for winter/dry conditions.

We received a 5er of it today, and it's currently sensitizing... we'll be coating screens with it tomorrow so I should have a report by monday or tuesday on how well they hold up

[ZooCity]

Whoa, that sounds great.  Do they have a version for HVP as well? 

This thread jinxed us, we had to pull a screen in under 100 impressions yesterday due to this issue.  It's dry in here now, around 20% humidity in the shop.  Going to try adding just a touch of distilled water to the HVP and see if it solves it. 

[ABuffington]

Yes we do a sell a more flexible version for winter.  Overnight temps in the shops can get quite low, and with cold blowing wind, no storm, the air is quite dry.  We offer SP-1400W which we sell in the midwest predominantly for this reason.  HVP does not have a winter version.  In some cases I have had companies install vaporizers to bring humidity up to 35%-50% in the screen rooms, but screens left set up overnight on press can be affected by cold dry air.  It's the cold/dry conditions that cause it.  We are not seeing it here in Socal where the humidity can get down to single digits.

Zoo City is correct, we do offer 1400W for winter printing and SP-7500 which was Engineered to be more flexible for long runs and has the same resolution and print qualities as SP-1400.  It is a dual cure that was designed for sim process type of work.

Al

[ZooCity]

We're at around 20-30% humidity, 60˚F in our screen room.  Conditions on the shop floor are about the same on humidity, more toward the 20% (maybe the humidistats we have only go down to around 20% and it's actually lower?) but the temp on the floor probably drops to around 50˚F overnight.  We can humidify the screen cab but humidifying the whole shop would not be practical. 

Any solution at all for users of stencils with HVP or similar?

[ABuffington]

We have not had many reports of HVP cracking. I have often wondered if washing the screen with warm water on press and drying with scrap t-shirts in the morning would help. 

We do have two new emulsions we are testing for textiles.  Murakami T3 for wb and discharge, no hardeners needed.  This requires a 5K+ Metal Halide or Starlight exposure.  (Again we haven't tested on the Vastex, Douthitt, Lightspeed, or other LED models at this point yet so I can't speak for them yet.)  Long exposure time on a 5k metal halide, 5-6 minutes.  Starlight would be a little over half of that from our initial test results.  For short run discharge and wb under 5k I'd stick with HVP or SP-1400. But if you library screens or have long runs it works great, with incredible resolution (better than SP-1400) and reclaim that is very easy. 

The other emulsion is TSR which is for High Solid Acrylic Inks.  Again designed for long run HSA inks and requires a hardener. 4 minutes on a 4k metal halide, 2'30" maybe on the Starlight.  While the long exposure seems time consuming, reshooting screens is more time consuming.  HSA is not waterbase or solvent, its a combination of both typically.  HSA will one continue to move into plastisol sales for large companies printing for major sports brands or companies.  It's soft hand and no PVC or Pthalates appeals to major retail brands.  It requires learning a new ink system and a matching emulsion like Murakami TSR that can withstand these new inks.

Both would print plastisol with ease.

Alan

[ZooCity]

We'll try a little rehydration on the HVP screens. 

Excited to check these out Alan, we're still down as always to beta for you and Murakami. 

An emulsion for HSA is long overdue.  You are correct in it's special requirements; it has all of the needs of a WB/DC stencil combined with much higher EOM requirements for opacity without printing this ink on a 28 station oval.  On top of all that it gets scrubbed down rigorously on press.  Tall order to fill for an emulsion.

5-6 minutes.  Starlight would be a little over half of that from our initial test results.

And here is where I had such a hard time explaining that we could really, seriously, use a 2up setup for LED exposure.  "Nah, it's super fast, you won't even need to shoot 2up" is absolutely true for plasti screens, not even close for HSA screens.  Still, 2.5min is way better than the 5-6min. that we currently are dealing with.  Our Olec bulb has even scorched the back of the reflector at this point.

[ABuffington]

Ok Chris looking for some beta testers for TSR for HSA inks and T3 for discharge and wb with no hardener needed.
Message me and I'll get you all some samples to test, expecially in winter weather.  I can also sample others who are interested.

Al

[Colin]

Got something that works well on a Nuarc 3140? 

Currently exposure times with the Saati PHU are 170 ltu for plastisol screens and 200 for waterbase screens for the Sure Loc 150/54 Murakami panels coated 2/2 sharp side with the PHU.  If you have something comparable I would love to try it out!

[ZooCity]

PM sent Alan.  We currently have an Olec 5kw setup, shooting 2up at 63" from glass.  Our Starlight arrived last week but was damaged in shipment so it will be another week or two before that gets installed.  If we hit the window we could trial on both potentially. 

Would the TSR work equally will across HSA/DC/WB/plasti?  Is the TSR a diazo added emulsion? I'm presuming the TSR has a higher build to eom per coat.  We harden all screens, have made that a very fast, efficient part of the process at this point, so non-permanent hardener is no problem and we do use Murakami A+B on the real long runs.  We do not post expose screens however.

Sorry to the original poster for the thread jack!

[jvanick]

so after a few days now with the SP1400W, here's our findings...

1. it's runnier than standard 1400...  and with the same coating technique seems to build a slightly thicker stencil... I forgot to bring our thickness meter to the shop, so I'm not 100% sure how much more it might be building.

2. it takes longer to expose... much longer.  26 seconds for standard SP1400, 40 seconds-ish for SP1400W on a 156 mesh.

3. when using it on the manual press it seems like it's a 'slicker' surface...

4. most importantly, NO BREAKDOWNS!  Even at 3500-4000 shirts, the screen looks great.

if the SP7500 is like this and is a year-round emulsion, I might look to switching to it, unless there's a significant cost difference.

[ZooCity]

Another Winter approaches and we're having the chatter breakdown/stencil cracking issues worse than ever.  It's very low humidity here, reading 14% on our basic digital hygrometer in the screen cabinet.  Xenon Nova, the emulsion we use nearly exclusively, held up ok last year to the dry climate but is struggling this.  We're upping the amount of water that we add to the dry diazo powder to see if it helps but I hate messing with the emulsion's viscosity too much.

Has anyone successfully tried to wet the screens down and then dry them before going on press or a similar fix?

How about Murakami TSR?  I see it's on the website now but no TDS.  Anyone out there using it during the Winter?

[jvanick]

We've since switched to Saati PHU-2 for faster exposure and better reclaim...

initially we were having some edge breakdown issues, but we narrowed the issues to the fact that we were coating screens at nearly 50% EOM.  once we got our screens into 20-25% EOM, the issues went away.

*the edge breakdown issues were JUST at the corners of the squeegees, the breakdown never continued into the middle of the stencil like it did with the SP1400.

Based on this, I'd check your emulsion thickness and see what it is...

[mimosatexas]

Do you round your corners?

[jvanick]

Do you round your corners?

yup... rounded...

just changing the EOM% seems to have fixed the issue...

[ZooCity]

It definitely happens on the higher eom screens.  Not exclusively but close to it.  I'd like to experiment with lowering eom but nows not the time.  We also need to start measuring consistently.

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